Growth hormone (GH) responses, prolactin (hPRL) responses, and growth patterns will be studied in children suffering from the hyperkinetic syndrome (minimal brain dysfunction), before and after beginning d-amphetamine therapy. GH responses to insulin tolerance tests, and during slow wave sleep will be measured before, one month, and six months after beginning treatment. Growth patterns will be assessed 3,6,12,18, and 24 months after treatment inception, and correlated with GH and hPRL responses.